Respiratory Illness, β-Agonists, and Risk of Idiopathic Dilated Cardiomyopathy

An epidemiologic study was carried out to examine the possible role of beta-agonists and other respiratory medications in the development of idiopathic dilated cardiomyopathy. Associations with respiratory medications, bronchial asthma, emphysema, and chronic bronchitis were examined by comparing newly diagnosed cases (n = 129) ascertained from five Washington, DC, area hospitals for the period 1990-1992 with neighborhood controls (n = 258) identified by using a random digit dialing technique. The cases and controls were matched on sex and 5-year age intervals and were compared in the analysis using conditional logistic regression methods. A statistically significant association was observed between idiopathic dilated cardiomyopathy and history of emphysema or chronic bronchitis (adjusted odds ratio (OR) = 4.4, 95% confidence interval (CI) 1.6-12.4). The association with bronchial asthma was of borderline significance (adjusted OR = 1.9, 95% CI 0.9-4.2). Associations were also observed with use of oral beta-agonists (adjusted OR = 3.4, 95% CI 1.1-11.0) and beta-agonist inhalers or nebulization (adjusted OR = 3.2, 95% CI 1.4-7.1), as well as with use of oral corticosteroids, inhaled corticosteroids or cromolyn, and theophylline medications. A total of 20.0% (23 of 115) of the cases had a reported history of beta-agonist inhaler use compared with 6.7% (17 of 254) of the controls. The strength of these associations was diminished when the temporal relation between exposure to beta-agonist inhalers or oral preparations and clinical diagnosis of idiopathic dilated cardiomyopathy was taken into account, however, and the associations with duration of beta-agonist medication use were not statistically significant (p > 0.05). The results of this study suggest, but do not prove, that use of beta-agonists has an etiologic role in idiopathic dilated cardiomyopathy.